The present invention relates to communication cable systems and, more particularly, to optical fiber clamping systems and methods for clamping optical fibers with the same.
An extensive infrastructure supporting telecommunication has been developed, traditionally based upon copper wire connections between individual subscribers and telecommunications company network distribution points. More recently, much of the telecommunications network infrastructure is being extended or replaced with an optical fiber based communications network infrastructure. The carrying capacity and communication rate capabilities of such equipment may exceed that provided by conventional copper wired systems.
As such, fiber optic cables are widely used for telecommunications applications where high information capacity, noise immunity and other advantages of optical fibers may be exploited. Fiber cable architectures are emerging for connecting homes and/or business establishments, via optical fibers, to a central location. A trunk or main cable may be routed, for example, through a housing subdivision and small fiber count “drop cables” may be spliced to the main cable at predetermined spaced apart locations.
A typical main cable may be installed underground and have multiple drop cables connected thereto, each of a hundred feet or more. Each of the drop cables, in turn, may be routed to an optical network unit (ONU) serving several homes. Information may then be transmitted optically to the ONU, and into the home, via conventional copper cable technology, although it also has been proposed to extend optical fiber all the way to the home rather than just to the ONU. Thus, the drop cables may serve groups of users, although other architectures may also employ a main cable and one or more drop cables connected thereto.
In addition to the optical fibers, a typical fiber optic cable may include cable jacketing material, cable strength members and fiber containment tubes. These three basic elements sometimes have different properties, such as different hardnesses, different stiffnesses, and different coefficients of thermal expansion. It may be desirable in many situations to limit or even prevent the cable jacketing and the cable strength members from axial displacement relative to one another, and/or relative to a cable enclosure or other device attached to the cable. A typical situation in which the securing is desired is where an opening has been made in the fiber optic cable for accessing the internal optical fibers, and where a splice enclosure may be installed.
In some existing systems, the securing of an accessed portion of a fiber optic cable may be achieved by first removing the cable outer jacket in order to expose some length of the strength members of the cable. The securing of the outer cable jacket is typically achieved by mechanically securing the outer cable jacket to a substrate at a location where the cable jacket is intact, i.e., outside of the region of the cable jacket that has been removed. This generally allows a circumferential clamp, such as a hose clamp or the like, to be tightened around the intact outer cable jacket, and then the clamp is attached to a substrate. In some cases, the clamp may be tightened around the full cable jacket and an extending element of the substrate so as to secure the cable outer jacket to the substrate. The cable strength element(s) are typically clamped in another clamp device, which is also attached to the substrate. This clamping may be achieved by various arrangements of screw actuated clamps and the like in order to bind down on and exert high forces upon the generally more rigid and harder strength member material. Thus, in combination, the clamping of the intact outer cable sheath to the substrate, and the clamping of the protruding exposed strength member(s) to the substrate can limit or even prevent displacement between the two, and can also serve as a means to jointly anchor the two to a device, such as a splice closure.
Generally, one reason for using two clamping mechanisms for the outer cable sheath and the strength members is that the cable jacket is relatively soft and, thus, usually requires a circumferential clamp that spreads the load over a surface area so as to avoid excessive point loading on the soft cable jacket material. The strength members are usually very hard materials, such as fiber glass or steel, and generally require much higher point loading to secure them sufficiently. These approaches generally require that the strength members be fully un-surrounded by the cable jacket materials (exposed) and protrude for some length in order to attach a clamp to them.